1. Field of the Invention
The present invention relates to a hoop molding method, which is one aspect of a molding method for embedding at least some of molded parts such as metal in a synthetic resin material.
2. Description of the Related Art
Electronic parts such as connectors oftentimes have a structure where some of their metal parts are embedded in a synthetic resin. So-called “hoop molding” is one aspect of a method of molding parts in which some of the metal parts are embedded in the synthetic resin material (for an example of hoop molding, see Japanese Patent Application Publication (JP-A) No. 2001-52556, which is described below).
In hoop molding, a pressing machine and a bending machine are arranged along the longitudinal direction of a long band-like base material, and frame portions are formed in the base material when the base material is fed to these machines from its leading end side. At the inner sides of the frame portions, molded portions are formed in a state where they are connected to the frame portions, and the molded portions are molded into metal parts as a result of being pressed and bent.
After the molded portions, which are intermittently formed in the base material in this state, have been pressed and bent as described above, they are disposed in a die for molding resin, and then some or all of the molded portions are embedded in synthetic resin and the molded portions are cut free from the frame portions.
Hoop molding has the advantage that production efficiency is high because the steps can be automated from the step of molding the molded portions to the step of molding the resin.
However, because hoop molding has a structure where the band-like base material is punched and the molded portions are molded in the frame portions, it is extremely difficult to cause plural molded portions to face each other in the thickness direction of the base material. It is possible to arrange and form plural molded portions in the width direction of the base material inside the same frame portion.
However, because the unbent shape of the molded portions is formed by punching the base material, when plural molded portions are to be arranged and formed in the width direction of the base material in the same frame portion, care must be taken to ensure that the length of one of the molded portions along the width direction of the base material does not overlap that of another molded portion. For this reason, there are many restrictions in terms of the dimensions of the molded portions.
Due to this, when forming parts where plural metal parts are integrally molded with a synthetic resin material, the step of a worker using tongs or the like to arrange and dispose the molded portions at predetermined positions inside the die oftentimes becomes necessary after punching the molded portions from plural base materials, and the advantage in hoop molding that all of the steps can be automated cannot be sufficiently exercised.
In view of the above circumstances, the present invention obtains a hoop molding method where automation is possible even in a structure including plural molded portions.